Full report - Conservation Gateway

Chapter 6 - Diadromous FishNo trend in abundance in spring or fall was observed forthe majority of sampled ten minute squares (Figures 6-2c,6-2d). There is evidence of a declining trend in springin the southern portion of the region, and an increasingtrend in the Gulf of Maine. Spring distributions at leastpartially reflect fish aligning themselves with natalwatersheds for spawning runs so this pattern is consistentwith observed declines in the southern range. In the fall,in a small area north of Cape Cod alewife increased insome TMS and decreased in some TMS. Since alewifeis a northern species that is believed to respond to temperaturecues by moving or migrating, these trends couldbe related to changes in ocean temperature, i.e., preferredtemperature zones might be shifting in a way that makesalewife more or less likely to be captured by bottomtendinggear.Alewife were highly persistent along the entire coast inspring, and consistently found in greatest abundancesacross southern New England, Georges Bank, and CapeAnn (Figure 6-3a). In fall, strongest persistence andabundance were in coastal waters along the Massachusettscoast north of Cape Cod and off downeast Maine and themouth of the Bay of Fundy (Figure 6-3b). The combinationof habitats represented by these maps is a reasonablerepresentation of important habitat areas for alewife inthree seasons; it may miss areas further south or offshorethat are used for overwintering.Important Marine Areas for AlewifeSpring: Southern New England, Georges Bank,and Cape AnnFall: Massachusetts coast north of Cape Cod,Downeast Maine, mouth of the Bay of FundyABFigure 6-3. Areas with high persistence and abundance over 40 years for alewife during the spring and fall seasons.Northwest Atlantic Marine Ecoregional Assessment • Phase 1 Report 6-